Methods of producing perforated nonwoven fabric



June 14, 1966 F. KALWAITES 3,255,496

METHODS OF PRODUCING PERFORATED NONWOVEN FABRIC Filed Nov. 1, 1963 5Sheets-Sheet 1 m Q U 0 0 &

ATTORNEY June 14, 1966 F. KALWAITES METHODS OF PRODUCING PERFORATEDNONWOVEN FABRIC 5 Sheets-Sheet 2 Filed Nov. 1, 1963 W W IMH LW [lama afa7 W4.

ATTORNEY June 14, 1966 F. KALWAITES 3,255,496

METHODS OF PRODUCING PERFORATED NONWOVEN FABRIC Filed Nov. 1, 1963 5Sheets-Sheet 5 r ET HR. @3

INVENTOR. rkwvx Klara/r55 muew '7 W4.

ATTORNE y United States Patent 3,255,496 METHODS OF PRODUCING PERFORATEDNONWOVEN FABRIC Frank Kalwaites, Somerville, N..I., assignor to Johnson& Johnson, a corporation of New Jersey Filed Nov. 1, 1963, Ser. No.320,688 7 Claims. (Cl. 19-161) This invention relates to nonwovenfabrics and to methods and apparatus for producing such nonwovenfabrics, i.e., fabrics produced directly from fibers without the use ofconventional spinning, weaving, knitting, or like fabricatingoperations.

Heretofore, nonwoven fabrics have been essentially different instructure from fabrics which have been woven or knitted. In a woven orknitted fabric, the natural or synthetic textile fibers making up thefabric do not occur individually, but are spun or twisted into yarns orthreads which in turn are woven or knitted into the finished fabric. Inthe well-known spinning operation, staplelength fibers are spun ortwisted together tightly into mechanical and frictional engagement withone another to form yarns which are substantially circular incrosssection. It is these yarns, and not the fibers acting individually,which serve. as the structural members of the resulting. woven orknitted fabrics. Generally speaking, these fabrics comprise reticularstructures of intersecting, intertwining yarns which define intersticesor openings between them.

Nonwoven fabrics have been primarily of two main types, felts and bondedwebs. In each of these, the fibers making up the fabric occurindividually and act individually as structural members. This is trueeven though the fibers in many felts are so highly interlocked andcompressed together that it is difficult to identify individual fibers.Hat felts, for instance, are extremely dense, relatively hard fabricswithout apparent interstices, which are quite dissimilar in appearanceand qualities to woven or knitted structures.

On the other hand, the fibers in bonded webs are usually flatly arrangedor organized in one or more layers, either more or less oriented oraligned in one predominant direction as in a card web, or assembled in arandom manner as in the air-laid-or water-laid isotropic web. Variousagents have been used to print an intermittent binder pattern of spacedbinder areas on such webs or to impregnate them completely over theirentire surface to hold the individual fibers together. In these types offabric, the fibers may remain relatively straight and over lapping onean other with very little interlocking between them. They are usuallyarranged in a more or less uniformly spaced condition in the plane ofthe web, in such a way that only very small randomly-occurringinterstices are apparent between the overlapped 'fibers and those fibersbetween interstices remain spaced and more or less flatly arranged,possessing little similarity to the yarns of woven or knitted fabrics.

The present invention contemplates a nonwoven fabric wherein the fibersare arranged preferably in a predetermined pattern to define holes oropenings with most of the fiber segments bordering the holes extendingin substantial alignment or parallelism with portions of the perimetersof the holes. In general, the fibers are arranged in interconnectedgroupings or web areas extending between the holes in a patterncorresponding to the pattern of holes. Closer study of the nonwovenfabric of the present invention reveals, among other characteristics,generally annular or elliptical, raised lips of accumulated individualfibers immediatley surrounding the holes, along with a plurality ofchannels comprising sloping sidewalls extending substantiallyuninterruptedly longitudinally of the nonwoven fabric between the holesand their raised lips. The resulting fabric may be made to resemble aparticular woven or knitted fabric.

The groupings or groups are connected by fibers extending from one toanother in such a way that they are common to a plurality of groupings.It is preferred that the average length of the fibers be considerablygreater than the lengths of the groups containing them with the resultthat the groups predominantly comprise only parts or segments of thefibers passing through them. Preferably, the fibers average at leastabout Mt inch in length or over and are textile-like in nature,extending up to about 2 /2 inches or even more in length. In general,the groupings are connected at junctures wherein the fibers extend in aplurality of diverse directions, while the fiber segments in the groupsare relatively aligned or parallelized with respect to one another andmore closely assembled than at the junetures.

In the foraminous structure formed by the interconnected fibergroupings, the fibers are in a state of mechanical equilibrium. Thefibers are mechanically and frictionally engaged to the extent that thearrangement of fibers is one of equilibrium.

Due to their structure and appearance and other qualities, fabricsproduced by the method and apparatus of this invention are particularlyadapted for use in surgical dressings, absorbent dressings such assanitary napkins and diapers, most suitably for covering sanitarynapkins and diapers, in wiping cloths, toweling, filter materials,lining materials, industrial base fabrics, as a substitute for gauze andgauze-like fabrics in general, and a variety of other applications.

The present invention contemplates nonwoven fabrics and methods andapparatus for producing such nonwoven fabrics preferably having apredetermined pattern of holes or openings therein from a starting layerof irregularly arranged, dry fibers by first impaling the dry fibrouslayer upon a group of prongs, pins or needles, preferably arranged in apredetermined pattern, then wetting the fibrous layer while impaled onthe prongs, brushing the wet fibers into fiber accumulating zones andchannels between the prongs, and finally removing the brushed layer ofwet fibers from the group of prongs.

The starting fibrous layer may be a nonwoven web of fibers, for example,natural, synthetic or man-made fibers, preferably cellulosic fibers,such as rayon or cotton. The individual fibrous elements of the layerare capable of movement under the influence of an applied mechanicalforce. In general, any of the starting materials described in thefollowing patents may be used as the starting materials in the methodsandapparatus of this invention: Griswold US. Patent No. 3,081,514, datedMarch 19, 1963; Griswold and Pearce U.S. Patent No. 3,081,515, datedMarch 19, 1963; and Kalwaites US. Patent No. 2,862,251, dated Dec. 2,1958. The preferred starting material is an unbonded fibrous web.

The preferred method of this invention involves the application ofexternal forces to a continuously moving layer of irregularly arrangeddry fibers impaled upon a group of prongs by wetting the fibers whilethey are so impaled, and then by brushing the fibers of successiveportions of the moving layer longitudinally, thereby moving individualfiber segments into positions within fiber accumulating zones andchannels in the interconnected spaces between the prongs, where they liein a state of mechanical equilibrium.

In a preferred embodiment of the apparatus of this invention, the prongsare carried on a rotatable cylinder against which a moving layer ofirregularly arranged, dry fibers is positioned. The layer of dry fibersis first passed into contacting engagement with the pointed ends of theprongs. An embedding brush rotating in a direction normal to theperipheral surface of the cylinder, progres sively presses successiveportions of the advancing layer of dry fibers downwardly about theprongs.

It has been determined that such pressing of dry fibers downwardly aboutthe prongs is far more easily accomplished in the case of dry fibersthan with wet fibers. Additionally, it has been observed that there issubstantially less breakage of fibers when dry fibers are presseddownwardly about the prongs than in the case of wet fibers.

The prongs upon which the starting fibrous layer is impaled before thebrushing action is carried out may have rounded, flat or pointed ends.They are preferably formed with a cylindrical or tapered body and long,gradually tapered conical points at their free ends. Conventionalmetallic card clothing, with the customary burrs removed from the freeends, may also be used. Prongs of various sorts are also suitable,including prongs having bodies of various cross-sectional shapes, round,oval, polygonal, etc., with chisel-shaped free ends.

The water or other aqueous medium which wets the fibrous layer on therotatable cylindrical surface acts as a lubricant and facilitates therelative movement between the individual fibers in the direction oftheir respective longitudinal axes. The relative longitudinal movementbetween individual fibers places the fibers in mechanical equilibrium sothat they remain in their rearranged positions in the resulting fibrouslayer.

The rotation of the cylinder pulls each portion of the layer of fibersprogressively past a series of rotary bushes disposed at right angles tothe direction of travel of the layer, with their bristles in contactwith the layer of fibers embedded about the prongs. These rotary brushespress the fibers downwardly about the prongs and toward the peripheralsurface of the rotatable cylinder.

The rotary brushes, which have axes which are parallel to thelongitudinal axis of the cylinder, move the individual fibers of thefibrous layer downwardly along the tapered sides of the prongs intocontact with the peripheral surface of the cylinder, laterally into thespaces between the prongs, and in the direction of their respectivelongitudinal axes, with respect to the other fibers in the layer, tocompact them in fiber accumulating zones and channels between theprongs.

In so doing, the brushes form a series of parallel, aligned channels orgrooves which are cut into the fibrous layer in the spaces betweentheholes surrounded by the previously mentioned raised lips. Thesechannels or grooves extend longitudinally and uninterruptedly forsubstantially the full length of the fibrous layer. The benefits andadvantages of such lengthwise channels will become clear from thefollowing discussion.

The resulting wetted and brushed fibrous layer is then removed from theprongs by passing it through the nip between a pair of doffing rollspositioned beyond the last of the rotary brushes. Either one of thedoffing rolls may be driven to insure continuous movement of the fibrouslayer away from the cylinder, or other suitable means may be providedbeyond the dofiing rolls to carry the fibrous layer into a drying area.It is obvious that the driven dotfer roll or means for moving thefibrous layer from the rotatable cylinder to the drying area must besynchronized with the circumferential speed of the cylinder.

Advantages of the invention other than those generally described abovewill be apparent from the following description and claims, takentogether with the drawings of preferred embodiments of the inventionwherein:

FIGURE 1 is a schematic, fragmentary side view, partly in section andpartly in elevation, of a machine embodying the invention, with aportion of the frame removed to clarify the illustration, the feed endto the machine being shown at the left and the discharge end on theright side of the figure;

FIGURE 2 is a schematic, fragmentary side view of a modification of themachine illustrated in FIGURE 1, showing another technique for applyingthe aqueous medium to the fibrous layer after it has been placed on therotatable cylinder;

FIGURE 3 is a schematic, fragmentary side view of a portion of themachine illustrated in FIGURES 1 and 2 showing in enlarged scale some ofthe details of the peripheral surface of the carrier for the fibrouslayer and the prongs thereon;

FIGURE 4 is a schematic, fragmentary side view of a modification of themachine and the fibrous web carrier of FIGURES 13;

FIGURE 5 is a schematic, fragmentary plan view illustrating a nonwovenfabric produced by the apparatus and methods of the inventive concept;

FIGURE 6 is a cross-sectional view of the nonwoven fabric of FIGURE 5,taken on the line 6-6 thereof; and

FIGURE 7 is a cross-sectional view of the nonwoven fabric of FIGURE 5,taken on the line 77 thereof.

In the embodiment of the invention shown in the drawings and withparticular reference to FIGURE 1 thereof, a fibrous layer 10 which ispreferably a card web is carried forwardly on a feed conveyor belt orother movable carrier 12 supported by a plurality of feed rolls 14, 16and 18 mounted for rotation in the frame 20 of the apparatus.

The fibers of the fibrous layer are natural, synthetic or man-madefibers, preferably cellulosic fibers, such as cotton or rayon, butsubstantially any textile length fiber or shorter fiber may be employed.These fibers are dry, which term is not intended to cover only bone-dryfibers but is intended to cover fibers containing approximately theirnormal moisture regain or thereabouts. In the case of cotton, conditionsof high temperature and high humidity could lead to the cotton fibertaking up as much as about 20 percent by weight of water without feelingdamp to the hand. This value of 20 percent for cotton is not an absoluteceiling for applicability of the present inventive concept and may beexceeded at times. Thus, it is merely being employed herein to generallydefine the term dry. This moisture-content value will vary according tothe fiber used, the operating conditions involved, and so forth.

The fibrous layer 10 is advanced by the movable conveyor 12 under arotatable guide-bar 22 mounted in hearings in the frame 20. Theguide-bar 22 is so located that it positions the fibrous layer 10 on thepoints 24 of a group of prongs 26 mounted in a predetermined pattern onthe peripheral surface of a rotatable cylinder 28. The rotatablecylinder 28 is mounted on a drive shaft 30 rotatably mounted in bearings32 in the machine frame 20 and is driven by a conventional driving means(not shown).

The rotatable cylinder 28 generally resembles a conventional doifingcylinder as found on a conventional textile card and the prongs 26 maybe positioned on the peripheral surface thereof in very much the samefashion as a steel band of metallic card clothing is helically wrappedaround and periphery of a doffing cylinder in conventional practice. Thesize, shape and spacing of the prongs 26 are as many and as varied asthe types of metallic card clothing found in the textile industry.Stainless steel is preferred as the material of which the prongs aremade.

The lower portion of the cylinder 28 dips into an immersion tank 34containing an aqueous medium 36 which wets the surface of the cylinder28. The aqueous medium consists normally only of water but, if desired,relatively small concentrations of various wetting agents, surfactants,antistatic agents, rust preventatives, dyes, pigments, fiber lubricatingagents, or other treating agents may be added. The purpose of wettingthe surface of the cylinder 28 will become clear from a furtherconsideration of this specification.

Rotation of the cylinder 28 progressively carries the fibrous layer 10forwardly on the prongs 26 in clockwise direction, as viewed in FIGURE1, under a rotatable brush 40 mounted on a shaft 42 in the machine frame20. The brush 40 extends the full width of the cylinder 28 but isconsiderably smaller in diameter. The working surface of the brush isformed by the ends or tips of the resilient, flexible brush bristleswhich have a low knee, near the. hub of the brush, with the major lengthof the wire bristle in the rake or bent position. The brush is sopositioned and is so rotated that the bristles progressively contact andpress the fibrous layer down the sides of the prongs 26 which penetratethe fibrous layer 10 and form therein a plurality of holes 38 in thelocal spaces correspondingly occupied by the prongs 26. Study of thefibrous layer also reveals the presence of annular or elliptical raisedlips 44 surrounding the holes 38 (seeFIGURE 5).

It is to be appreciated that the fibers of the layer 10 are dry duringthis positioning and penetrating step and consequently they are moreeasily moved aside and rearranged into the new perforated configuration.If the fibers had been wet, more resistance to penetration andrearrangement would have been offered and more fibers would have beenundesirably ruptured or broken.

Care should be exercised that the brushing action not be too severe ortoo harsh as to damage the fibers by rupturing or breaking them.Accurate positioning and adjusting of the bushes with respect to theperipheral.

surface of the cylinder 28 is therefore necessary.

Brush 40 and other similar brushes to be described more fullyhereinafter rotate with a peripheral linear speed which is greater thanthe peripheral linear speed of the rotatable cylinder 28. The ratio ofthe peripheral linear speeds (brush:cylinder) is generally on the orderfrom about 2 /z:1 up to about :1. Greater speed ratios are, Of course,possible particularly with brush bristles which are more flexible andsofter.

As the fibers move downwardly on the prongs 26 and finally reach theperiphery, of the cylinder 28, they come into contact with the water oraqueous medium adhered thereon. Absorption of the aqueous medium by thefibers is very rapid and the fibers may be considered as wet as they areleaving the penetrating zone occupied by the rotatable brush 40.

' fibrous webs but is not as satisfactory for heavy fibrous websinasmuch as the amount of aqueous medium picked up by and remainingadhered to the rotatable cylinder 28 after it leaves the immersion tank34 is limited and may not sufliciently wet out 'a heavy fibrous web tothe desired degree. In order to provide additional aqueous medium, thefollowing procedure'may be followed. A relatively open, low count,absorbent fabric or similar material 50 (see FIGURE 3), such as gauze,scrim, lace, netting, or other relatively open, low count fabric, istightly wrapped around'the periphery of the cylinder 28 under suchtension that it penetrates the tips of the prongs 26 and contacts thesurface of the cylinder 28 itself. The absorbent material 50 ispreferably made from absorbent yarns, such as cotton or rayon, and thuscan absorb considerable amounts of the aqueous medium. If desired,several wraps of such absorbent fabric may be made round the cylinder28, thus creating a greater capacity or source of available aqueousmedium.

, It is not essential that the absorbent material 50 be a fabricatedproduct. Yarn or string may be used and may be tightly wrapped aroundthe rotatable drum 28 to be positioned on the surface thereof betweenthe prongs 26. Bleached cotton twine is especially suit-- able for sucha use.

Upon passage through the immersion tank 34, the absorbent material 50takes up a considerable amount of aqueous medium and subsequentlytransfers a substantial portion of the same to the fibrous layer 10 whenit is pressed thereagainst by the rotating brush 40. The

amount of the aqueous medium transferred can be controlled by decreasingor increasing the number of wraps of absorbent fabric on the cylinder,selecting a more open or less open fabric, or thickeror thinner twine,and so forth.

In FIGURE 2, there is illustrated still another technique for wettingthe fibrous layer after it has been positioned and penetrated by theprongs on the rotatable cylinder. A humidifier head or atomizer spray 51provided with a nozzle 52 may be positioned adjacent the rotatablecylinder 28 at a zone subsequent in clockwise direction to thepositioning and penetrating zone. The amount of aqueous medium appliedto the fibrous layer 10 can be very easily controlled in this manner byadjusting the nozzle 52 or by using other equivalent flowcontrol means.

The wet, perforated fibrous layer is then advanced on the periphery ofthe rotatable cylinder 28 and is guided under additional rotatablebrushes 56 and 58 which brush the fibrous layer as it passes thereby.Brushes 56 and 58 are .usually similar in construction to brush 40. Ifdesired, only one brush may be employed or, if required, a total ofthree, four or more brushes may be used.

The brushes 56 and 58 are positioned in such proximity and adjacency tothe rotatable cylinder 28 and the fibrous layer thereon that thebrushing of the fibrous layer is relatively thorough but gentle andcreates therein a plurality of channels or grooves 60 (see FIGURES 57)which extend substantially uninterruptedly and continuously for the fulllength of the perforated fibrous layer. These channels 60 extend betweenthe holes 38 and their surrounding raised lips 44. It is to be notedthat these channels 60 are relatively straight and are actually cut intothe body of the fibrous layer, possessing beds and sidewalls 59 whichextend substantially uninterruptedly the full length of the fibrouslayer in the longitudinal direction thereof. Such sidewalls 59 areactually formed; they are not indirectly created by the raising of thelips 44 around the holes 38.

It is often desirable to have the bristles of the brushes 40, 56 and 58progressively come closer and closer to the peripheral surface of therotatable cylinder 28. Thus, the clearance at the first zone (brush 40)may cause a light pressing of the fibrous layer against the wet surfacein order to transfer the desired aqueous medium. The second brush 56brushes more heavily and begins to create the desired channels. Thethird brush 58 brushes most heavily and completely forms the desiredchannels 60.

Consideration of FIGURES 5-7 will indicate the nature and the advantagesof the fibrous layer which is produced by the techniques of the presentinvention. The holes 38 and their surrounding slightly raised lips 44which are formed thereabout naturally atfectthe porosity of the fibrouslayer and affect the fiow of fluids therethrough. The continuouslengthwise channels 60 affect the flow of fluids along the surface ofthe fibrous layer and thus control and direct such flow in thelengthwise direction rather than in the widthwise direction. This isdesirable when the fibrous layer is to be used as a cover for a sanitarynapkin, or in a surgical dressing, etc.

A trough or dimple 61 is observed in the fibrous layer and is bounded bythe raised lips 44 of two adjacent holes 38, as measured in thelengthwise direction, and by the raised sidewalls 59 of two adjacentchannels, as measured in a widthwise direction. This trough is dimpleshaped and forms a depression in the fibrous layer.

The fibrous layer 10, after having been perforated and brushed, isremoved from the surface of the rotatable cylinder 28 by any desireddoffing means, such .as a pair of rotatable nip rolls 64 and 66. Ifdesired, the nip rolls 64 and 66 may be pressed together with such forcethat they press the fibrous layer together and flatten the conveyor beltsubstantially horizontal.

raised lips 44 into a more compacted, more planar configuration.

The fibrous layer is then forwarded for additional processing, drying,printing or impregnating with a binder material, or other handling ortreating by means of a movable discharge conveyor 68 supported ondischarge rolls 70, 72 and 74 rotatably mounted in the frame 20.

Removal of the fibrous web in a wet condition provides advantages overprocedures using dry fibrous webs throughout. Dofiing of a Wet fibrousweb is considerably easier than dofiing of a dry fibrous web.Additionally there is considerably less fiber spring-back which wouldtend to close up the holes which have just been formed. The holes aretherefore cleaner, sharper and more uniform.

In FIGURE 4, there is illustrated a modification of the apparatusdisclosed in FIGURES l3. In FIGURE 4, there is disclosed a fibrous web111 which is advanced by a movable feed conveyor belt 113 supported byrotatable feed rolls 115 into contact with the prongs, pins or needles117 located on a movable conveyor belt 119. The movable conveyor belt119 is supported and driven by one of a pair of rotatable cylinders 121and 123 mounted upon shafts 125 and 127 in bearings 129 and 131 in themachine frame 133. Cylinder 123 is preferably the driving cylinder.

Consideration of FIGURE 4 will reveal that the fibrous web 111 isadvanced onto the points of the prongs 117 of the movable conveyor belt119 and is advanced under rotatable brushes 135, 137 and 139 in a verysimilar manner to that described previously in connection with FIGURESl-3. The positioning and penetrating action by the rotatable brush 135is very similar to the positioning and penetrating function of therotatable brush 40 in FIGURE 1. The operation of the rotatable brushes137 and 139 is very similar to the operation of the rotatable brushes 56and 58 of FIGURE 1. A spray nozzle 141 may be employed in a very similarway to the spray nozzle 52 in FIGURE 2. An absorbent fabric 143 may alsobe employed on the conveyor belt 119 in the same manner and for the samefunction as the absorbent material 50 in FIGURE 3.

The fibrous layer advances from left to right in FIG- URE 4 and, afterhaving been positioned, perforated, wetted and brushed, is removed fromthe prongs 117 of the conveyor belt 119 by a discharge conveyor 145supported by discharge rolls 147. Nip rolls which apply pressure, ifdesired, to the fibrous layer may also be used for such removalpurposes, similar to the nip rolls 64 and 66 of FIGURES 13. A rotatablesupporting roll 149 may be employed to keep the upper reach of the If itis decided to employ an immersion tank similar to the immersion tank 34of FIGURE 1, such may be done by using an immersion roll 151 whichcauses the conveyor belt 119 to dip down into an immersion tank 153containing water or aqueous medium 155 to be wetted thereby.

The invention will be further illustrated in greater detail by thefollowing specific examples. It should be understood, however, thatalthough these examples may describe in particular detail some of themore specific features of the invention, they are given primarily forpurposes of illustration and the invention in its broader aspects is notto be construed as limited thereto.

Example I The starting fibrous layer is a 45-inch width oriented cardweb comprising a blend of 50% dull and 50% extra dull viscose rayonstaple fibers having a staple length of about 2 inches and a denier of1.5. The web weight is approximately 300 grains per square yard.

This fibrous layer is processed through the apparatus illustrated inFIGURE 1. The rotatable cylinder has a diameter of 27 inches and issubstantially identical to a dofiing cylinder normally used in textilecarding operations. Its peripheral surface is helically covered withstainless steel metallic card clothing. Five layers of 20 x 12 bleachedcotton gauze are Wrapped tightly around the rotatable cylinder as shownin FIGURE 3.

The rotatable brushes have outside diameters of about 8 inches and thebristles are substantially identical to fancy roll clothing such as usedin the textile industry.

In this specific case, the brush is made by taking a 6 /2-inch outsidediameter base roll and helically wrapping thereon a l /z-inch wide,6-ply (32 ounce), heavy, rubber foundation in which have been embeddedl-inch staple wire, plated, low bend, fancy roll clothing.

The bristles have relatively low knees near the hub of the brush, asindicated in'FIGURE 1. The aqueous medium is water to which has beenadded about 0.1% by weight of a surface active agent. The water pick-upis about 150% by weight.

The resulting perforated, brushed nonwoven fabric is delivered to thedischarge conveyor and is found to possess the holes, lips, channels andsidewalls illustrated in FIGURE 5. There are approximately 176 holes persquare inch, each hole measuring about 0.020 x 0.050 inch. The brushednonwoven fabric is then over-all impregnated with a polyvinyl acetatebinder.

It is noted that the holes naturally affect the flow of fluids throughthe nonwoven fabric whereas the raised lips around the holes and thesubstantially uninterrupted continuous lengthwise channels affect theflow of fluids along the surface of the nonwoven fabric, controlling anddirecting such flow in the lengthwise direction rather than in thewidthwise direction. Such characteristics are desired in absorbentmaterials wherein flow control of fluids deposited thereon is required.

Example 11 The procedures set forth in Example I are carried outsubstantially as set forth therein with the exception that cotton fibershaving a staple length of about 1% inches are used instead of theviscose rayon staple fibers in forming the starting fibrous layer. Theresults are comparable.

Example III The procedures of Example I are carried out substantially asset forth therein with the exception that the web weight is reduced from300 grains per square yard to about grains per square yard.Additionally, the gauze fabric is removed from the rotatable cylinder.

The light-weight web is sufficiently wetted by the aqueous medium pickedup by the rotatable cylinder and the results are generally comparable.

Example IV The procedures of Example I are followed substantially as setforth therein with the exception that the gauze fabric wrapped on therotatable cylinder is removed and an atomizing spray nozzle, asillustrated in FIGURE 2, is used to apply moisture to the fibrous layer.The results are generally comparable.

Example V The procedures of Example I are followed substantially as setforth therein except that the absorbent material on the rotatablecylinder is a bleached cotton twine which is wrapped helically on thesurface of the rotatable cylinder between the prongs thereon.

The results are comparable to those obtained in Example I.

Example VI The procedures of Example I are followed substantially as setforth therein except that the apparatus of FIG- URE 4 is employed usingthe spray nozzle, as shown. The results are comparable.

Although several specific examples of the inventive concept have beendescribed, the same should not be construed as limited thereby nor tothe specific techniques or elements mentioned therein but to includevarious other equivalent techniques and elements as set forth in theclaims appended hereto. It is understood that any suitable changes,modifications and variations may be made without departing from thespirit and scope of the invention.

What is claimed is:

1. A continuous method of converting a layer of dry fibers into anonwoven fabric having holes therein arranged in a predetermined patternwhich comprises: embedding said layer of dry fibers on a group ofprongsarranged in a predetermined pattern to form holes havingsurrounding raised lips in said layer of dry fibers; wetting said layerof fibers with an aqueous medium while embedded at the base of saidgroup of prongs; brushing said layer of wet fibers in the area betweensaid prongs to form channels between said lips and longitudinally ofsaid layer; and removing the brushed layer of wet fibers from said groupof prongs.

2. A continuous method of converting a layer of dry fibers into anonwoven fabric having holes therein arranged in a predetermined patternwhich comprises: penetrating said layer of dry fibers with a group ofprongs arranged in a predetermined pattern; positioning said layer aboutthe base of said prongs to form holes having surrounding raised lips insaid layer of dry fibers; wetting said layer of fibers while it is sopositioned; brushing said layer of wet fibers in the areas between saidprongs to form channels between said lips and longitudinally of saidlayer; and removing the brushed layer of wet fibers from said group ofprongs.

3. A continuous method of converting a layer of dry fibers into anonwoven fabric having holes arranged in a predetermined pattern andhaving channels located between said holes which comprises: penetratingsaid layer of dry fibers with a group of prongs arranged in saidpredetermined pattern; positioning said layer about the base of saidprongs to move segments of the fibers from the local spaces in the layeroccupied by the prongs whereby holes having surrounding raised lips areformed in said fibrous layer; wetting said layer of fibers while sopositioned; brushing said layer of wet fibers in the areas between thelocal spaces occupied by said prongs to form channels between said lipsand longitudinally of said layer; and removing the brushed layer of wetfibers from said group of pnongs.

4. A continuous method of converting a layer of dry fibers into anonwoven fabric having holes arranged in a predetermined pattern andhaving channels located between said holes which comprises: penetratingsaid layer of dry fibers with a group of prongs arranged in saidpredetermined pattern; positioning said layer about the base of saidprongs to move segments of the fibers from the local spaces in the layeroccupied by the prongs whereby holes having surrounding raised lips areformed in said fibrous layer; spraying said layer of fibers with anaqueous medium while so positioned; brushing said layer of wet fibers inthe areas between the local spaces occupied by said prongs to formchannels between said lips and longitudinally of said layer; andremoving the brushed layer of wet fibers from said group of prongs.

5. A continuous method of converting a layer of dry fibers into anonwoven fabric having holes therein which comprises: placing said layerof dry fibers on the points of a group of prongs arranged in saidpredetermined pattern; pressing said layer of dry fibers against saidgroup of prongs whereby holes having surrounding raised. lips are formedin said fibrous layer and said layer of dry fibers moves from the pointsof said prongs to the bases of said prongs into contact with a surfacethereat wet with an aqueous medium; maintaining said layer of fibers incontact with said wet surface for a sufiicient time to wet said layer offibers; brushing the layer of wet fibers in the areas between the localspaces occupied by the prongs to form channels between said lips andlongitudinally of said layer; and removing the brushed layer of wetfibers from said group of prongs.

6. A continuous method of converting a layer of dry fibers into anonwoven fabric having holes arranged in a predetermined pattern andhaving channels located between said holes which comprises: wetting agroup of prongs arranged in a predetermined pattern and an absorbentmaterial located adjacent the bases of said prongs with an aqueousmedium; placing said layer of dry fibers on the points of a group ofprongs arranged in said predetermined pattern; pressing said layer ofdry fibers against said group of prongs whereby holes having surroundingraised lips are formed in said fibrous layer and said layer of dryfibers moves from the points of said prongs to the bases of said prongsinto contact with said wetted absorbent material; maintaining said layerof fibers in contact with said wet absorbent material for a sufficienttime to wet said layer of fibers; brushing the layer of wet fibers inthe areas between the local spaces occupied by the prongs to formchannels between said lips and longitudinally of said layer; andremoving the brushed layer of wet fibers from said group of prongs.

7. A continuous method of converting a layer of dry fibers into anonwoven fabric having holes arranged in a predetermined pattern andhaving channels located between said holes which comprises: wetting agroup of prongs arranged in a predetermined pattern and an absorbentmaterial located adjacent the bases of said prongs with an aqueousmedium; placing said layer of dry fibers on the points of a group ofprongs arranged in said predetermined pattern; pressing said layer ofdry fibers against said group of prongs whereby holes having surroundingraised lips are formed in said fibrous layer and said layer of dryfibers moves from the points of said prongs to the bases of said prongsinto contact with said wetted absorbent material; maintaining said layerof fibers in contact with said wet absorbent material for a sufficienttime to wet said layer of fibers; brushing the layer of wet fibers inthe areas between the local spaces occupied by the prongs to formchannels between said lips and longitudinally of said layer; removingthe brushed layer of wet fibers from said group of prongs; and applyingpressure to the brushed layer of wet fibers to flatten the same.

References Cited by the Examiner UNITED STATES PATENTS 1,854,481 4/1932Mudd 19-161 1,978,620 10/ 1934 Brewster 2872.2 X 2,647,065 7/1953-Scholl 264l56 X 2,862,251 12/1958 Kalwaites 19-161 3,025,585 3/1962Griswold '19161 X 3,040,412 6/1962 Russell 2872 3,081,501 3/1963Kalwaites 19-161 3,081,512 3/1963 Griswold 2872 3,081,515 3/1963Griswold 161-109 3,101,520 8/1963 George et al. 19-161 X 3,104,9989/1963 Gelpke 161109 DONALD W. PARKER, Primary Examiner.

ROBERT R. MACKEY, Examiner.

1. A CONTINUOUS METHOD OF CONVERTING A LAYER OF DRY FIBERS INTO ANONWOVEN FABRIC HAVING HOLES THEREIN ARRANGED IN A PREDETERMINED PATTERNWHICH COMPRISES: EMBEDDING SAID LAYER OF DRY FIBERS ON A GROUP OF PRONGSARRANGED IN A PREDETERMINED PATTERN TO FORM HOLES HAVING SURROUNDINGRAISED LIPS IN SAID LAYER OF DRY FIBERS; WETTING SAID LAYER OF FIBERSWITH AN AQUEOUS MEDIUM WHILE EMBEDDED AT THE BASE OF SAID GROUP OFPRONGS; BRUSHING SAID LAYER OF WET FIBERS IN THE AREA BETWEEN SAIDPRONGS TO FORM CHANNELS BETWEEN SAID LIPS AND LONGITUDINALLY OF SAIDLAYER; AND REMOVING THE BRUSHED LAYER OF WET FIBERS FROM SAID GROUP OFPRONGS.